Construction of the Mita Bellju Building, a Superhigh-Rise Building with a Base Isolation Layer at a Height of 114 Meters, Is Completed

—Will ensure safety and security by efficiently reducing overall shaking of the building.—

May 10, 2012Takenaka Corporation

Takenaka Corporation (President: Toichi Takenaka) will complete construction on May 31 of the Mita Bellju Building, which it designed and constructed. This building, a superhigh-rise with maximum height of 163.95 meters, is a multilayer complex facility. It consists of an underground parking area, 1st and 2nd floors occupied by shops, and 4th to 24th floors of steel structure which will be used for offices. Apartments are located on its 25th to 33rd floors of reinforced concrete structure. A base isolation layer installed at 114 meters above ground level (under the 25th floor) which divides the building functionally will be able to efficiently reduce shaking of the overall building by absorbing most seismic energy. The cross-section plan which places residential space above offices is intended to satisfy Minato Ward’s requirement to make efforts to include residential space in buildings※.

The crisscross lattice-shaped louvers, which are a major unique feature of the exterior of the building, are intended primarily to block sunlight and were designed to be kind to the environment. The columns on the office floors at and above the 4th floor are narrow columns installed uniformly on the periphery of the building at 3.6 meter intervals to match the louvers. In the lower floors, the columns are installed at intervals of 10.8 meters and from the 3rd to the 2nd floor, every three columns are bundled to become one column, in order to expand the entrance space and increase the efficiency of the underground parking area.

Because of restrictions on the lines of motion of work vehicles imposed by the extremely narrow space facing the site road, during construction the inverted construction method was implemented from the first story to simultaneously construct the aboveground and underground stories, shortening the work period.

※Requirement to make efforts to include residential space

Clearly set forth in Article 9 of the Guideline to Promoting Permanent Residency through Development Projects in Minato Ward.
In the case where a developer plans to develop a building with total floor space of 3,000 square meters or more, the developer shall strive to provide good quality residences and facilities convenient for daily life occupying floor area equal to 10 percent of the total floor area.

Special features of the exterior design

Planning the exterior design based on the idea that the building will become a district landmark and providing the highest part (residential floors) with a distinctive stepped silhouette ensures that even when seen from a great distance, people will recognize at a glance that it is the Mita Bellju Building. To mitigate the effects of the eccentricity of the center of gravity of the highest part of the building, a result of the shape of the building, a structural control system has been installed, consisting of a base isolation layer installed at an intermediate floor.

Characteristics of the use of the building

On the office floors, a pleasant office environment has been created by, in addition to providing the exterior louvers, designing the offices with ceilings three meters in height and installing a natural ventilation system along with an air barrier system. Each floor of the office space is fully equipped with common elements including a lounge and a smoking room facing the windows and multipurpose toilets. Privacy of the occupants of the residential floors is protected by special elevators separate from the elevators to the office floors. The shops at the bottom of the building are laid out to enclose a plaza and an entrance hall atrium, a plan intended to attract customers to the highly visible store area.